Abstract
The study sought to determine the duration of standing needed to detect most cases of orthostatic hypotension (OH) in the emergency room (ER) and to correlate OH with symptoms, hospitalization and survival. Patients attending a tertiary‐center ER within a 2‐month period underwent orthostatic tests after 1, 3 and 5 min of standing. OH was defined as a drop of ⩾20 mmHg in systolic pressure or ⩾10 mmHg in diastolic pressure on assuming an upright posture. Of the 814 patients tested (402 men, mean age 56.6±19.9 years), 206 (25.3%) had OH, detected in most cases (83.5%) after 3 min of standing. OH was associated with significantly higher supine systolic (p = 0.013) and diastolic (p = 0.004) blood pressure, symptoms of syncope (r = 0.11, p<0.001) or dizziness (r = 0.14, p<0.0001) and risk of hospitalization (50.9% vs 22.9%, p<0.0001). Crude mortality was similar between patients with and without OH (13.8% vs 8.7%, p = 0.06). However, on age‐adjusted analysis, patients older than 75 years with OH had significantly increased mortality (p = 0.04). In conclusion, 3 min of standing is apparently sufficient for the diagnosis of most cases of OH. Considering the high rate of OH and its predictive value for hospitalization, it should be routinely assessed in all ER patients.
Introduction
Orthostatic hypotension (OH), first described by Bradbury & Eggleston [1] in 1925, is defined as a reduction of a least 20 mmHg in systolic blood pressure (BP) or at least 10 mmHg in diastolic BP within 3 min of standing. OH is a common finding in older persons, with a prevalence of 6–30% [2–4]. The prevalence of OH in patients presenting to the emergency room (ER) as well as the prevalence of OH in the general population is not clear.
OH is a physical sign and not a disease. However, it has important implications for prognosis in some patient subgroups. It is an independent risk factor for stroke in middle‐aged subjects [5] and elderly patients [6], and it is associated with an increased risk of coronary artery disease [7]. Some studies have shown increased mortality in subjects with OH [4],[8,9].
OH may be symptomatic or asymptomatic. Symptoms include lightheadedness, dizziness, nausea, palpitations, tremulousness, headache and neck ache [10]. They usually appear on assumption of an erect posture from a recumbent position or following head‐up tilt, and usually resolve on return to the recumbent position. Some investigators reported that 1 min of standing is all that is needed to detect clinically important OH [11], whereas others found signs of OH after 13–30 min of standing [12].
The primary aim of this prospective study was to assess the necessary duration of the standing position for the detection of most cases of OH in the ER. The secondary aim was to determine the possible correlation of OH with symptomatology, hospitalization and 1‐year survival.
Methods
Study population
This prospective study was conducted in the ER of Rabin Medical Center, a 1000‐bed tertiary hospital, from 1 July to 31 August 2001. The investigator made 50 visits to the ER during that period and tested 20 consecutive patients each time, in order to recruit approximately 1000 patients to the study. Patients who could not stand up for medical reasons were excluded.
For each patient examined, we recorded demographic data, reason for referral to the ER and hospital admission. In patients in whom OH was detected, data was recorded as to coexisting illnesses and medication usage. The physician who determined if the patient required hospitalization was unaware of the postural changes in blood pressure recorded by the investigator. One‐year mortality was calculated from the death certificate files of the Ministry of Interior.
The study was approved by the institute’s Helsinki Committee. All patients provided oral permission for the blood pressure measurements.
Blood pressure measurements
Subjects were instructed not to smoke or drink any fluids containing caffeine for 30 min before measurements were taken. Supine heart rate and blood pressure (BP) were measured after at least 5 min of complete bed rest using an electronic BP monitor (BP‐8800, Colin Corporation, Japan). The width of the BP cuff was adjusted to cover 80% of the upper arm. After the supine measurements, the subject was asked to rise to a standing position and to rest his/her arm on a Mayo stand placed at heart level. The rate of detection of OH was assessed after 1, 3 and 5 min of standing. OH was defined as a reduction in systolic BP of at least 20 mmHg or in diastolic BP of at least 10 mmHg [10]. Any complaints of dizziness and syncope during the postural measurements were recorded.
Statistical analysis
Pearson and Spearman correlation coefficients were calculated between the variables. Continuous variables are presented as mean±SD. To analyze relationships in the distribution of categorical variables, the chi‐squared or Fisher’s exact text was used, as appropriate. To analyze differences in mean continuous parameters between two groups, Student’s t‐test was used. Comparison of mean continuous parameters of more than two groups was done by analysis of variance with the Duncan multiple comparison option. A multivariable stepwise logistic regression model was fitted to the data in order to predict OH by other variables. p‐values less than or equal to 0.05 were considered statistically significant.
Results
Patient characteristics
Of the 895 study candidates who presented to the ER during the designated period, 81 were unable to maintain a standing position and were excluded from the analysis: 28 had dementia, 21 refused to stand, 11 had a fractured leg, six had a suspected cervical fracture, three were unconscious, three had leg pain, two were connected to a respirator, two had sepsis, two were confused, one had paraparesis, one had abdominal pain and one complained of general weakness. The final sample included 814 patients (402 men and 412 women) of mean age 56.6±19.9 years.
The patients’ background data, time of day examined and main reason for referral to the ER are summarized in Table I. Most of the patients (64%) were examined in the ER section of internal medicine, followed by the sections for surgery (24%) and orthopedics (12%). About half (51%) arrived between 08.00 and 16.00 h, 37% between 16.00 and 24.00 h, and 12% between 24.00 and 08.00 h. The distribution of the patient visits among the different sections and their timing were in accordance with the data recorded for the same 2 months in the previous year.
Table I. Characteristics of 814 patients tested for OH in the ER.
OH was diagnosed in 206 patients (25.3%): 46 patients (22.3%) had systolic OH, 107 patients (52.0%) had diastolic OH and 53 (25.7%) had both. OH was detected after 1 min of standing in 107 patients (51.9%), after 3 min of standing in 37 patients (31.6%) and after 5 min of standing in 19 patients (16.5%).
Factors associated with OH (Table I)
Age
A significantly higher prevalence of OH was noted in patients aged 60–>75 years compared to patients younger than 60 years (p = 0.0004).
ER section
Patients examined in the internal medicine section of the ER had a significantly higher rate of OH than patients examined in other sections (p = 0.05).
OH and supine BP measurements
Patients who had OH had a significantly higher supine systolic BP (p = 0.013) and diastolic BP (p = 0.004) than patients who did not.
Time of day
The time of day examined had no effect on the prevalence of OH.
Reason for referral to the ER
With the exception of falls (p = 0.008) and kidney disease (p = 0.05), the detection of OH was not strongly associated with presenting complaints, as listed in Table I.
Symptoms
More patients with OH had symptoms during orthostatic measurements in the ER. Specifically, of the eight patients who experienced syncope, six (2.9%) had OH and two did not (0.3%) (p<0.0004), and of the 151 patients who complained of dizziness, 58 (28.2%) had OH and 93 (15.3%) did not (p<0.0001). A significant correlation was found between syncope or dizziness and OH (r = 0.11, p<0.001 and r = 0.14, p<0.0001, respectively).
OH and coexisting illnesses
The most common coexisting illnesses in the patients with OH were: hypertension (53.5%), ischemic heart disease (40.1%), varicose veins (34.4%), diabetes (28.07%) and Parkinson’s disease (10.2%).
OH and medication usage
The most common medications used in patients with OH were ACE inhibitors – 26.8%, diuretics – 25.5%, beta‐blockers – 24.2% and calcium‐channel blockers – 22.3%.
Hospitalization
The rate of hospital admission was significantly higher in the OH group than the non‐OH group (50.9% vs 22.9%, p<0.0001).
Mortality
Mortality was assessed 1 year following the study period from data provided by the Ministry of Interior. A borderline difference was found in crude mortality between patients with and without OH (13.8% vs 8.7%, p = 0.06). However, on age‐adjusted analysis, patients older than 75 years with OH had a significantly higher rate of mortality (p = 0.04).
Discussion
Most of the published studies on the prevalence of OH were conducted in the elderly population and reported a wide range of values, from 6% to 30% [2],[4]. These rates were even higher when orthostatic tests in the elderly were repeated throughout the day, reaching 48–68% [13–15]. In acutely ill older inpatients, OH was detected in 64.5% on initial morning standing up following nocturnal rest [16].
Ours is the first study to assess the prevalence of OH in the ER. We detected OH in about 25% of the tested subjects after 1, 3 and 5 min of standing. The cumulative rate of detection after 1 and 3 min of standing was 83.5%, indicating that the 5‐minute measurement may be omitted under ER conditions, where relatively little time is allocated for physical examination. The prevalence of OH was higher in those with high supine systolic and diastolic blood pressure, in accordance with other studies [3],[13],[16].
Older patients (60–>75 years) had a higher prevalence of OH than younger ones (<60 years). This difference may be attributable to age‐related physiological changes in the cardiovascular system and a blunted response to the recruitment of the sympathetic system [17]. Older patients also have serious underlying diseases, such as diabetes mellitus and Parkinsonism, which increase the risk of OH, and many of them receive drugs that could cause OH.
With the exception of falls and kidney disease, the detection of OH was not strongly associated with a range of presenting complaints. Although the rate of patients presenting because of falls was lower than expected from previous data, we assume this discrepancy may be explained by the relatively young age of our sample.
Syncope and dizziness during OH measurement occurred more frequently in patients with OH than in those without. However, the very small number of patients with syncope precludes any definitive conclusion regarding this issue. A better estimate can be derived from a recent study in which the prevalence of OH was assessed only in patients presenting to the ER with syncope. Among 650 such patients, 156 (24%) had OH [18].
The OH group had a greater proportion of hospital admissions than the non‐OH group. As the admitting physician was unaware of the patients’ OH status, this factor did not contribute to his/her decision to hospitalize the patient. These findings may suggest that ER referrals with OH are sicker than ER referrals without OH. It is possible that at least some of the affected patients were dehydrated, which may have contributed to the OH.
The association between mortality and OH has been assessed previously, though the results are controversial. Some studies reported increased mortality [4],[8,9] whereas another did not [19]. In our study, age‐adjusted analysis revealed that patients over 75 years with OH had a significantly higher mortality rate (p = 0.04). The increase in morality may be due to co‐morbidity of patients with OH.
In conclusion, in the ER setting, OH may be detected in most cases after 1 and 3 min of standing. Considering the high rate of OH in ER referrals in the present study, and the significant association of OH and hospitalization and (in elderly patients) mortality, we suggest that OH be measured routinely in all ER patients.
| All patients | Patients with OH (n = 206) | Patients without OH (n = 608) | p‐value | |
|---|---|---|---|---|
| Age (year), | ||||
| Mean±SD | 56.6±19.9 | 60.4±20.2 | 55.3±19.8 | |
| <60, n (%) | 421 (51.7) | 82 (39.8) | 339 (55.8) | |
| 60–75, n (%) | 220 (27.0) | 69 (33.5) | 151 (24.8) | |
| >75, n (%) | 173 (21.3) | 55 (26.7) | 118 (19.4) | 0.004 |
| Sex, n (%) | ||||
| Male | 402 (49.4) | 94 (45.6) | 308 (50.7) | 0.21 |
| Female | 412 (50.6) | 112 (54.4) | 300 (49.3) | |
| Clinical data, mean ±SD | ||||
| Supine SBP | 144.9±27.7 | 149.0±28.6 | 143.4±27.3 | 0.013 |
| Supine DBP | 78.0±15.4 | 80.7±15.4 | 77.1±15.4 | 0.004 |
| Supine HR | 79.8±16.2 | 80.8±17.3 | 79.4±15.8 | 0.27 |
| ER section, n (%) | ||||
| Internal medicine | 523 (64.3) | 144 (69.9) | 379 (62.3) | 0.05 |
| Surgery | 195 (24.0) | 43 (20.9) | 152 (25.0) | 0.23 |
| Orthopedics | 96 (11.7) | 19 (9.2) | 77 (12.7) | 0.26 |
| Time of day, n (%) | ||||
| 08.00–16.00 h | 421 (51.7) | 111 (53.9) | 310 (51.0) | 0.47 |
| 16.00–24.00 h | 298 (36.6) | 74 (35.9) | 224 (36.8) | 0.81 |
| 24.00–08.00 h | 95 (11.7) | 21 (10.2) | 74 (12.2) | 0.44 |
| Reasons for referral to ER, n (%) | ||||
| Abdominal pain | 216 (26.5) | 48 (23.3) | 168 (27.6) | 0.22 |
| Chest pain | 142 (17.4) | 32 (15.5) | 110 (18.1) | 0.40 |
| Febrile state | 40 (4.9) | 9 (4.4) | 35 (5.1) | 0.67 |
| Dizziness/vertigo | 35 (4.3) | 8 (3.9) | 27 (4.4) | 0.73 |
| Syncope | 22 (2.7) | 7 (3.4) | 15 (2.5) | 0.48 |
| Arrhythmia | 20 (2.5) | 8 (3.9) | 12 (2.0) | 0.13 |
| Falls | 11 (1.4) | 7 (3.4) | 4 (0.7) | 0.008 |
| Kidney disease | 9 (1.1) | 5 (2.4) | 4 (0.7) | 0.05 |
| Seizure | 8 (1.0) | 4 (1.9) | 4 (0.7) | 0.12 |
| Others | 311 (38.2) | 78 (37.9) | 233 (38.3) | 0.91 |
OH, orthostatic hypotension; SBP, systolic blood pressure; DPB, diastolic blood pressure; HR, heart rate.
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